1. Field of the Invention
Apparatuses consistent with the present general inventive concept relate to an image forming apparatus. More specifically, the present general inventive concept relates to a fixing device, which is used in the image forming apparatus.
2. Description of the Related Art
An image forming apparatus, such as a printer, a facsimile, a copier, a multifunction unit (MFU), or the like, forms an image on a print medium by using electrophotography. In general, to form the image, the image forming apparatus performs an electric charging process, a light exposing process, an image developing process, an image transferring process, and an image fixing process. In the electric charging process, a charging unit charges a photosensitive body with a given potential. In the light exposing process, an optical scanning unit scans a light onto the photosensitive body charged with the given potential thus to form an electrostatic latent image corresponding to print data on the photosensitive body. In the image developing process, a developing unit supplies a toner onto the photosensitive body on which the electrostatic latent image is formed, thus to form a toner image on the photosensitive body. In the image transferring process, a transfer unit transfers the toner image formed on the photosensitive body onto the print medium. In the fixing process, a fixing device fixes the toner image transferred onto the print medium thus to form the image on the print medium. After that, the print medium is discharged to the outside of the image forming apparatus, and the print operation is completed.
In general, the fixing device applies a heat and a pressure onto the print medium to fix the unfixed toner on the print medium. Accordingly, the fixing device includes a heating unit, which consumes a considerable amount of electric power to generate the heat. Actually, the fixing device may consume more than 50% of an entire amount of electric power consumption of the image forming apparatus. Thus, it is desirable to provide a fixing device that uses the heat generated from the heating unit as efficiently as possible.
Even though the image forming apparatus is turned on, the fixing device does not fix the unfixed toner immediately, and requires a warm-up time during which the fixing device reaches a temperature that effectively fixes the unfixed toner. Since waiting for a warm-up time causes an inconvenience to a user, it is necessary to reduce the warm-up time.
In addition, if a fixedness of the toner is deteriorated, the toner may get on a user's hands when the print medium that finishes print process is rubbed with the user's hands. Thus, it is also necessary to improve the fixedness of the toner.
As described above, there is a need to develop a fixing device able to satisfy all of conditions, which reduce the electric power consumption, reduce the warm-up time, and enhance the fixedness of the toner.